Solution chemistry synthesis, morphology studies, and optical properties of five distinct nanocrystalline Au-Zn intermetallic compounds

Au-Zn was used as a prototype binary system for exploring intermetallic phase accessibility in nanoparticle systems using low-temperature solution chemistry methods. By reacting Au nanoparticles with diethylzinc (Et2Zn) in oleylamine at temperatures of 250-300 degrees C, nanoparticles of five distinct binary intermetallic compounds were accessible: Au3Zn, Au5Zn3, AuZn, Cu5Zn8-type gamma-(Au,Zn), and Mg-type epsilon-(AuZn). A variety of nanoparticle shapes, including spheres, triangles, hexagons, and rods, are accessible in the Au-Zn system via a pseudomorphic reaction of Au nanocrystal shapes with Et2Zn. The Au-Zn nanoparticles have optical properties that vary with Zn content, ranging from a surface plasmon resonance peak at similar to 495 nm for Au3Zn to absorption in the ultraviolet region for the Zn-rich phases. (C) 2009 Elsevier B.V. All rights reserved.